Vehicles used in transportation, e.g. trucks, buses, and cars, are surrounded by various zones which are often visually inaccessible to the vehicle operator during the vehicle's operation. These zones are commonly known as "blind spots" and are a significant source of danger encountered in the operation of any vehicle. Accordingly, injury to person and property may result from a vehicle operator's inability to adequately view the various blind spot zones surrounding the vehicle.
Traditionally, mirrors have been used to provide vehicle operators with views of various zones surrounding the vehicle and minimize blind spots. However, mirrors still leave blind spots and, in some cases, may cause greater danger where the vehicle operator has a false sense of security in utilizing his mirrors. Often vehicle operators, e.g. automobile drivers, have the mistaken belief their mirrors provide them with adequate viewing capability. In larger vehicles, e.g. trucks and buses, mirrors cannot be used to view certain zones, e.g. the zone directly behind a bus or truck.
Mirrors also have certain physical limitations that limit their utility as vehicle viewing devices. Mirrors may distort the vehicle operator's view of a particular area and/or provide inadequate views of certain zones, e.g. the zone immediately in front of or behind a vehicle. Mirrors are impractical for viewing objects in zones at the back of multiple truck trailers because plane mirror images are small. Additionally, inherent imperfections in mirror surfaces disperse reflected light, thus distorting light images and, at night they can increase glare. Mirrors are also subject to fogging in various weather conditions. Even when the mirrors are heated to reduce fogging, this does not solve the problem where fogged windows on the vehicle cab itself may prevent the operator from utilizing the mirrors. Further, mirrors are relatively expensive due to the cost of the mirror itself and the wind resistance and corresponding loss of fuel economy due to their presence on the vehicle exterior.
Recent developments have suggested use of video systems combined with traditional mirrors to minimize blind spots. These video systems comprise a video camera and monitor together with their associated electronics. However, video systems are relatively expensive, and often provide a poor view to the vehicle operator. These systems also have significant potential for frequent repair due to the substantial number of mechanical and electronic parts which are subject to breakdown under the harsh operating environment associated with vehicles and the severe weather conditions in which they frequently operate. Accordingly, a need exists for a vehicle viewing system that is inexpensive, reliable and provides a high quality view of any and all designated areas, e.g. a blind spot at the back of a second truck trailer, to the vehicle operator.
In this regard, the present invention is a vehicle viewing system which enables the vehicle operator to view various "blind spot" visual zones around his vehicle. The present invention comprises an objective assembly mounted on the vehicle so that its field of view covers a blind spot or other view zone. The image from the objective assembly travels via an image relay system to a viewer assembly mounted in the cab of the vehicle for viewing by the vehicle operator. The image relay system can comprise a conventional fiber optic cable periscope assembly may be also added between the objective assembly and the viewer assembly to view zones more than forty feet from the vehicle operator. Inherent physical limitations in fiber optic cables of a diameter suitable for use with a vehicle viewing device restrict image transmission to about forty feet before light loss severely limits the image utility. The image produced at the viewer assembly is a substantially true image of the field of view of the objective assembly. The present invention provides for either a non-reversed image or a mirror image which emulates traditional rear-view mirrors.
Specifically, the objective assembly comprises a housing having a glass aperture through which a large field of view image passes through to a lens system and to the receptor end of a fiber optic cable. A mirror may be added to direct the image into the lens system when the objective assembly can not be positioned to directly cover the desired field of view. The image passes through the length of the fiber optic cable to emerge at the emitter end of the fiber optic cable into a periscope assembly or directly into a viewer assembly comprising a housing with a mounting aperture and a viewing aperture. Ultimately, the image enters the viewer assembly and is directed through a suitable lens so that the vehicle operator can easily perceive the large field of view image covered by the objective assembly.
The viewer assembly may include an optional lens system through which the light passes to create a brighter image to the operator. A series of mirrors or a prism configuration may be added to the viewer assembly to reverse the image viewed at the viewing aperture and emulate a rear-view mirror. A roof prism or amici prism may be utilized in this regard.
In a further alternative embodiment, multiple objective assemblies and their corresponding image relay systems may be connected to a single viewer assembly. In this embodiment, the viewer assembly has a split screen capability wherein the image emitted from each image relay system is directed through a different area of a single viewing aperture. Thus, one viewer assembly may be used for viewing multiple images.
If a periscope assembly is used, an objective assembly which omits the mirror may be used. The periscope assembly incorporates a flexible fiber optics or conventional optics mount, thus allowing the objective assembly to cover any field of view. The flexibly mounted objective assembly directs an image through a lens system to the receptor end of a fiber optic cable. The image passes through the length the fiber optic cable to emerge at the emitter end of the cable and into an interface with the periscope assembly. The interface comprises a field lens which collects the light and focusses it on a relay lens. In turn, the relay lens creates an image four focal lengths from the end of the fiber optics emitter. The image then passes through another field lens. The periscope assembly transports the light image through alternating field and relay lenses. Ultimately, the light image is collected by a final lens mounted within an initial interface. The final lens focusses the light image on another fiber optic cable. The second fiber optic cable may be interfaced with another periscope assembly, or a viewer assembly.
The present invention is a passive viewing system, i.e. it has no mechanized or electronic parts. As a result, operational failure due to mechanical or electronic parts failure is minimized. The low profile of portions of the viewing system mounted on the exterior of the vehicle, e.g. the objective assembly, the periscope assembly and portions of the fiber optic cable, may reduce the wind resistance of the vehicle. Thus utilization of the viewing system over traditional viewing systems may result in realization of fuel savings and lower costs of operation. Further, the present invention forms intermediate images, rather than reflecting and dispersing light in the manner of plane or curved mirrors. Such image collection can result in more accurate images, with less glare, which is particularly important at night when the contrast between ambient light and automotive headlights is greater.
The present invention may also include an infra-red filtering system to decrease potential damage or fire hazards resulting from sunlight focussed on the objective assembly. The infra-red filtering system comprises a hot mirror coated lens and a cold mirror housed within the objective assembly. The hot mirror reflects infra-red rays while the cold mirror allows the majority of the remaining infra-red rays to pass through the mirror rather than being reflected with the visible ray. The infra-red filtering system may eliminate up to ninety-six percent of infra-red rays entering the objective assembly, thus reducing potential damage to the fiber optic cable.